Format the x-axis ticks@firefly: You can have a look at the official documentation. However, it's not very comprehensive when it comes to examples or so. Basically you do something like ax.xaxis.set_major_formatter( FuncFormatter(your_formatter) ), where your_formatter is a function that takes the arguments x and pos, where x is the "tick value" (eg. 150) and pos the position, and returns a string which is printed at the tick marks. A small example (although pylab) is given here.